Authors: Christian Kaare Paaskesen, MD, and Magnus Balslev Avnstorp, MD

Introduction

Lip lacerations are common facial injuries encountered in emergency and surgical practice.

Because the lips play a central role in both facial aesthetics and essential functions such as speech, eating, and expression, even small defects can have significant functional and cosmetic consequences. Accurate assessment and meticulous repair are therefore critical to restore both appearance and oral competence. The complexity of lip anatomy, with its layered structure of skin, muscle, and mucosa, as well as the distinct vermilion border, requires a systematic approach to evaluation and closure.

Misalignment of just 1-2 mm at the vermilion border may result in a visible deformity, while inadequate repair of the orbicularis oris muscle can compromise oral function. Careful wound assessment, knowledge of local vascular supply, and an understanding of appropriate suture techniques are essential prerequisites for optimal outcomes. This chapter outlines the principles of assessment, preparation, and layered closure of lip lacerations, with emphasis on restoring function, maintaining symmetry, and minimizing scarring.

Illustration of open mouth with uvula visible. — Figure 1 | **Patient with laceration of the lower lip**
The patient presented to the emergency department with a laceration involving the lower lip.

Assessment

Systematic evaluation is essential. Determine depth, orientation, and involvement of key landmarks such as the vermilion border and commissure. Palpate for orbicularis oris disruption and check for foreign bodies, dental trauma, or tissue loss. Always mark the vermilion border before anesthesia and swelling, since even a 1-2 mm misalignment is highly visible.

Mouth anatomy with preoperative marking diagram — Figure 2 | **Preoperative marking of the vermilion border**
One of the most important steps in achieving a cosmetically pleasing result. Marking should be performed before anesthesia, as the vermilion border may become less distinct afterward.

Preparation

Careful preparation is key to a successful outcome. Regional nerve blocks provide excellent anesthesia without tissue distortion. Irrigate thoroughly and perform only minimal debridement to preserve tissue. Achieve hemostasis without compromising vascularity.

Vascular Supply

The lips are supplied by the superior and inferior labial arteries, giving robust perfusion and promoting healing. This allows conservative debridement, but crush or high-tension injuries require close evaluation of blood flow to guide repair decisions.

Diagram showing lip anatomy and layers. — Figure 3 | **Assessment of anatomical structures**
Before wound closure, the anatomical layers of the lip must be identified. In lacerations with skin loss or irregular margins, careful debridement may be necessary.

Layered Closure

Repair must follow the layered anatomy of the lip. Re-approximate the orbicularis oris with absorbable sutures to restore sphincter function. Close mucosa with fine absorbable sutures, while skin and vermilion border require non-absorbable monofilament. The first stitch is always placed at the vermilion border to ensure perfect alignment.

Illustration of oral suture technique with close-up view. — Figure 4 | **Approximation of the orbicularis oris muscle**
Absorbable sutures, in this case 4-0 Vicryl, are used to approximate the orbicularis oris muscle. Proper repair is essential to restore oral sphincter function and long-term mouth function.

Illustration of cleft palate in a person's mouth. — Figure 5 | **Approximation of the orbicularis oris muscle**
The muscle layer is re-approximated and secured before proceeding with closure of the superficial layers.

Suture Techniques

Select suture material and size according to tissue layer: absorbable for mucosa and muscle, fine non-absorbable for skin and vermilion. Precision and gentle tissue handling are critical to achieve functional and aesthetic success.

Diagram of oral cancer surgery in mouth. — Figure 6 | **Approximation of the superficial layers**
When closing the superficial layers, the first stitch should always be placed at the vermilion border. For the mucosal layer, absorbable sutures such as 5-0 Vicryl Rapide are appropriate, while for the vermilion and dermal portions of the laceration, non-absorbable sutures such as 5-0 nylon (e.g., Dafilon) are preferred.

Illustration showing mouth surgery details. — Figure 7 | **Approximation of the superficial layers**
The superficial layers are closed. Care should be taken to avoid excessive tension on the sutures, as this may lead to hypertrophic scarring or suture marks.

Restoring Function and Aesthetics

The goals of repair are restoration of oral competence, preservation of symmetry, and minimization of scarring. Proper muscular repair prevents functional deficits, while precise vermilion border alignment maintains natural contour. Gentle technique, timely suture removal, and appropriate postoperative care further enhance long-term results.

Pearls

Mark the vermilion border before infiltration or swelling; even 1 mm misalignment is visible
Use a regional nerve block (infraorbital or mental nerve) for better anesthesia and less tissue distortion than local infiltration.
Irrigate thoroughly but debride conservatively — lips have excellent vascularity and heal well.
Repair in layers: orbicularis oris first, then mucosa, then skin/vermilion.
Choose fine sutures (5-0, 6-0 or 7-0 nylon/prolene for skin; 4-0/5-0 absorbable for mucosa and muscle).
Place the first stitch at the vermilion border to ensure perfect alignment.
Undermine gently if needed to reduce tension, but preserve vascularity.
Remove cutaneous sutures early (about 5 days) to minimize track marks.

Pitfalls

Misalignment of the vermilion border, the most common and most noticeable error.
Excessive tissue debridement, which risks cosmetic deformity.
Ignoring muscle repair, leading to oral incompetence or notching.
Using large or absorbable sutures on skin, causing unnecessary scarring.
Over-tightening sutures, resulting in ischemia or “railroad track” scars.
Failing to check for associated dental, gingival, or facial fractures.
Neglecting aftercare instructions (sun protection, scar massage), which worsens long-term appearance.

Lip trauma